Effects of corticosterone and dietary energy on immune function of broiler chickens.

Jiachang Yang,Yufeng Wang,Zhigang Song,Ardashir Sheikhahmadi,Hongchao Jiao,Congcong Li,Lei Liu,Hai Lin,Shu-Biao Wu

doi:10.1371/journal.pone.0119750

Jiachang Yang, Yufeng Wang + Show 7 more

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https://doi.org/10.1371/journal.pone.0119750

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Abstract

An experiment was conducted to investigate the effects of dietary energy level on the performance and immune function of stressed broiler chickens (Gallus gallus domesticus). A total of 96 three-day-old male broiler chickens (Ross × Ross) were divided into two groups. One group received a high energy (HE) diet and the other group received a low energy (LE) diet for 7 days. At 5 days of age, the chickens from each group were further divided into two sub-groups and received one of the following two treatments for 3 days: (1) subcutaneous injection of corticosterone, twice per day (CORT group; 2 mg of CORT/kg BW in corn oil) and (2) subcutaneous injection of corn oil, twice per day (Control/Sham treatment group). At 10 days of age, samples of blood, duodenum, jejunum, and ileum were obtained. Compared with the other three groups, the LE group treated with CORT had the lowest average daily gain (ADG) and the poorest feed conversion ratio (FCR, P < 0.05). Furthermore, CORT treatment decreased the relative weight (RW) of the bursa independent of the dietary energy level, but it decreased the RW of the thymus only in the chickens fed the LE diet. By contrast, CORT administration decreased the RW of the spleen only in the chickens fed the HE diet (P < 0.05). The plasma total protein, albumin, tumor necrosis factor alpha, interleukin 2 and immunoglobulin G (IgG) levels were affected by the CORT treatment (P < 0.05); however, these factors were not significantly affected by the dietary energy level. Toll-like receptor-5 mRNA level was down-regulated by CORT injection in the duodenum and ileum (P < 0.05) and showed a trend of down-regulation in the jejunum (P=0.0846). The present study showed that CORT treatment induced immunosuppressive effects on the innate immune system of broiler chickens, which were ameliorated by consumption of higher dietary energy.

Highlights

Stress is a widely used term in biology that describes a set of physiological and behavioral responses elicited by adverse stimuli
The levels of total protein (TP), Alb, tumor necrosis factor-α (TNF-α), interleukin 2 (IL-2), and immunoglobulin G (IgG) in the plasma were affected by the CORT treatment (P < 0.05); the dietary energy level did not affect these parameters (P > 0.05, Table 4)
Biochemical changes may have been responsible for the lower growth rate of the CORT-exposed broiler chickens

Summary

Introduction

Stress is a widely used term in biology that describes a set of physiological and behavioral responses elicited by adverse stimuli. Corticosterone and Broiler Immunity face different types of stressors, such as high temperature, high stock density, and diseases that may impair productive performance and survival, thereby resulting in financial losses for farmers [1, 2]. The total energy budget must be optimally divided between different physiological functions, such as thermoregulation, growth, and reproduction. In this context, the total energy balance or physiological condition may determine the ability of individuals to mount an optimal immune response [3]. Immune functions have been traditionally regarded as maintenance requirements, but there is increasing evidence of the sensitivity of immunity to nutrient supply [4]. The experimental induction of the immune system increases energy expenditure and negatively affects energy metabolism [6]

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